To use SMSD as a daemon, you might want to use init script which is shipped
with Gammu in contrib/init directory. It is not installed by default, either
install it manually or check INSTALL file for instructions.

Under Windows 7 you might need to disable UAC (user account control) before
you will be able to install SMSD service.

If Gammu fails to start as a Windows service (you will usually get “Error
1053: The service did not respond to the start or control request in a timely
fashion”), first check your SMSD logs. If they do not contain any useful hint,
try starting SMSD manually with exactly same parameters as you installed the
service (without -i).

For example the command line can look like:

gammu-smsd.exe -c smsdrc

You now should be able to get errors from SMSD even if it fails to start as a
service.

You can not use same phone by more programs in same time. However in case you
did not enable locking in [gammu] section, it might be able
to start the communication with phone from more programs. In this case neither
of the programs will probably work, see Invoking Gammu and suspending SMSD for
workaround.

There is no way to detect that SMS message is reply to another by looking at
message headers. The only way to achieve this is to add some token to the
message and let the user include it in the message on reply.